In-room breathing motion estimation from limited projection views using a sliding deformation model

17th International Conference on the Use of Computers in Radiation Therapy

物理学;计算机科学

Delmon, V.^1 ; Vandemeulebroucke, J.^2,3 ; Pinho, R.^1 ; Vila Oliva, M.^1,4 ; Sarrut, D.^1 ; Rit, S.^1

Université de Lyon, CREATIS, Léon Bérard Cancer Center, F-69373 Lyon, France^1

Vrije Universiteit Brussel (VUB), Department ETRO, Pleinlaan 2, B-1050 Brussels, Belgium^2

IMinds, Department FMI, Gaston Crommenlaan 8 (box 102), B-9050 Ghent, Belgium^3

IMagX Project, ICTEAM Inst., Université Catholique de Louvain, Louvain-la-Neuve, Belgium^4

关键词: B-spline representation;    Cone-beam projection;    Deformable registration;    Deformation modeling;    Digitally reconstructed radiographs;    Normalized correlation coefficient;    Piecewise-continuous;    Target registration errors;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/489/1/012026/pdf
DOI  :  10.1088/1742-6596/489/1/012026

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

Purpose: To estimate in-room breathing motion from a limited number of 2D cone-beam (CB) projection images by registering them to a phase of the 4D planning CT. Methods: Breathing motion was modelled using a piecewise continuous B-spline representation [1], allowing to preserve the sliding along the thoracic wall while limiting the degrees of freedom. The deformed target 3D image was subsequently used to generate Digitally Reconstructed Radiographs (DRR). The Normalized Correlation Coefficient (NCC) between the measured projection images and the DRR was computed in the 2D projection space. However, the partial derivatives of the NCC relative to the transform parameters were backprojected into the 3D space, avoiding the projection of the transform Jacobian matrix which is computationally intractable [2]. Results: The method was quantitatively evaluated on 16 lung cancer patients. 40 CB projection images were simulated using the end-exhale phase of the 4D planning CT and the geometric parameters of a clinical CB protocol. The end-inhale phase was deformed to match these simulated projections. The Target Registration Error (TRE) decreased from 8.8 mm to 2.0 mm while the TRE obtained from the 3D/3D registration of the reconstructed CBCT was significantly worse (2.6 mm), due to view aliasing artefacts. We also provide the motion compensated image reconstructed from a real CB acquisition showing the quality improvement brought by the in-room deformation model compared to the planning motion model. Conclusions: We have developed a 2D/3D deformable registration algorithm that enables in-room breathing motion estimation from cone-beam projection images.